chore: make ext fns mut

[mattsse]

additional docs and make ext functions mut

[rkrasiuk]

lgtm pending doc fixes

[codecov]

Codecov Report

Merging #4081 (9bb2e47) into main (c0abfce) will increase coverage by 0.00%.
The diff coverage is 0.00%.

Files Changed	Coverage Δ
bin/reth/src/args/rpc_server_args.rs	53.98% <0.00%> (ø)
bin/reth/src/cli/ext.rs	1.78% <0.00%> (ø)
bin/reth/src/node/mod.rs	12.50% <0.00%> (ø)

... and 6 files with indirect coverage changes

Flag	Coverage Δ
integration-tests	16.54% <0.00%> (+<0.01%)	⬆️
unit-tests	64.08% <0.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
reth binary	25.67% <0.00%> (ø)
blockchain tree	83.04% <ø> (ø)
pipeline	90.07% <ø> (ø)
storage (db)	74.41% <ø> (ø)
trie	94.70% <ø> (ø)
txpool	48.36% <ø> (ø)
networking	77.43% <ø> (ø)
rpc	57.87% <ø> (-0.01%)	⬇️
consensus	64.08% <ø> (ø)
revm	32.59% <ø> (ø)
payload builder	6.58% <ø> (ø)
primitives	88.01% <ø> (+0.02%)	⬆️